It is known that alkali metal bisulphites may be added to double bonds activated by electron-attracting groups such as nitrile or ester groups [cf. R. T. E. Schenck and J. Danishefsky, J. Org. Chem. 16, 1683 (1951); O. Bayer, Ang. Chem. 61, 233 (1949)]. It is also known that bisulphites may be added to aliphatic double bonds which are only weakly activated. Thus, the addition of bisulphites to allyl alcohol is described in the literature [cf. M. S. Kharasch, E. M. May and F. R. Moyo, J. Org. Chem. 3, 1975 (1939)]. This reaction produced 3-hydroxy propane sulphonic acid in the form of its salts in a yield of only 30%. Although the yield of this reaction was increased (see, e.g. German Pat. No. 915,693), it was not possible to suppress the formation of secondary products which are assumed to be compounds of the following structure: ##STR1## Additionally, complete separation of the inorganic salts formed during the reaction from the sulphonate is difficult.
Salts of 3-hydroxy-2-hydroxy methyl propane sulphonic acid are also known and can be obtained by reacting 2-methylene-1,3-propane diol with bisulphites (see, e.g. German Offenlegungsschrift No. 2,224,304). However, 2-methylene-1,3-propane diol can only be obtained in small quantities at considerable expense, so that the salts of 3-hydroxy-2-hydroxy methyl-1-propane sulphonic acid obtained therefrom cannot be used on a wide scale. In addition, it is relatively difficult to separate the salts of 3-hydroxy-2-hydroxy methyl propane sulphonic acid from the inorganic salts formed during the reaction. This also applies to the production of salts of 1,4-dihydroxy-2-butane sulphonic acid which may be used for the preparation of stable baths for copper plating in the absence of an electrical current (see, e.g. German Offenlegungsschrift No. 2,132,003).
Accordingly, there is a need for dihydroxy sulphonate which may be produced easily and inexpensively and which, in addition, may be used for a variety of applications by virtue of their favorable properties.